This invention relates cryogenic to a container, generally called a "dewer" for a coolant liquid, such as liquid nitrogen or liquid helium, and more particularly to a container for industrial vacuum apparatuses, which is used to supply and collect such a coolant to and from a cooling trap of a circulation system.
A conventional coolant preservation container has, as shown in FIG. 2, a container member in the inner side of an inner wall 6 of the container, wherein the inner wall 6 is surrounded by a vacuum space 5. A coolant 7 injected into the container member is taken out from a recovery port 2 so as to be practically used. In order to supply a coolant to a cooling trap, which is provided in, for example, a vacuum device, and which is adapted to be cooled by passing a coolant therethrough, according to a conventional method using the coolant preservation container of FIG. 2, it is necessary that the coolant or discharged from the cooling trap is introduced or changed into another container.
When a coolant is stored in separate containers as mentioned above, the cooling heat of the coolant which is necessarily held in the plurality of containers is apt to be rapidly lost thereby causing the coolant to be consumed at a high rate. A conventional container of this kind is inconvenient to handle, and the container is bulky.